Re: [EnergyPlus_Support] HVAC Link Diagram and Mass flow rate calculation

["Michael J. Witte" <mjwitte@xxxxxxxx>]

1.  This appears to be a bug in HVAC Diagram (or in the way EnergyPlus writes 
the bnd output file).  In simulations with both air loops and fan coil units, 
it appears that only the first fan coil unit will be drawn.  If the air loops 
are removed from the simulation, all of the fan coil units draw.  A bug report 
has been posted (CR 6500).

2.  The mass flow errors listed below, and the different yet similar plant flow 
errors you were getting with earlier versions of these files were very tricky 
to track down.  The problem is in the order of branches in the BRANCH LIST 
object.  EnergyPlus simulates the branches in a loop in the order in which they 
are listed in the BRANCH LIST.  This means that the branches must be listed in 
flow order.  So, the plant loop inlet branch (with the pump) must always be the 
first branch in the list.  Then the parallel branch(es) are listed next.  The 
order is not significant among the parallel branches.  The loop outlet branch 
must be listed last.  Reordering the branches in your input files gets rid of 
the mass flow errors.  I apologize that it took so long to catch this.  A 
suggestion has been posted to make this requirement more obvious in the 
documentation and to possibly implement an automatic check so that an 
appropriate error message can be issued to pinpoint the problem (CR6502).  The 
corrected BRANCH LISTS are pasted in below.

Mike




On 2 Nov 2004, at 1:21, wing sun lee wrote:

> 
> Hi,
> 
> Problem: 
> 1. The HVAC link graph only show the FCUs for LG4, but I don't why the other
> zones can not display.
> 
> 2. {
>   ** Warning ** Error -- Mass Flow Rate Calculation in Plant Loop=CHILLED WATER
>   LOOP SYS_2, Outlet and Inlet differ by more than tolerance.
>    **   ~~~   ** Loop inlet node=CW SUPPLY INLET NODE 2,
>    flowrate=0.000000000000000E+000 **   ~~~   ** Loop outlet node=CW SUPPLY
>    OUTLET NODE 2, flowrate=2.38898710063452
> }
> 
> Please help me.
> 
> Thanks,
> 
> SAMLEE
> 
> Encl.
> 
> 
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> 
> [Non-text portions of this message have been removed]
> 
> 
> 
> 
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> 
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> 






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